My mean green hornet

Hi Jim,

Why do you wish to use the P38 power steering pump as opposed to the P6B item? The latter bracket and pump will attach in exactly the same way and location to the 4.6 block as it does to the 3.5 P6B block.

If you do run the 4.6 timing cover, the water pump is designed to run in the opposite direction. The P38's have their thermostat located within a sealed plastic housing that fits into the lower radiator hose. The thermostat, which open at 96 degrees C, cannot be changed nor removed. As the water pump foot prints are distinct, a P6B water pump cannot be used on the 4.6 timing cover.

Ron.
 
stina wrote,...
But think on we have to start them when it's minus ? degrees over here at times .
Click to expand...

Hi Stina,

I have been in sub zero locations during Winter with my Rover, rest assured the difference between the two as I mentioned above remains the same.

Ron.
 
Thanks Ron, learning as I go :)
Ideally I did want to use the existing p6 PAS pump, just didn't know how possible it was.
Is it possible to swap the pulley onto the nose so the serpentine belt can drive it though?
So it looks like the engine is destined to run with the higher stat then.
Jim
 
I wonder if there would be anything detrimental to running the SU's at the higher coolant temperature. Range Rover's weigh at least 2 ton against the P6 at something a bit over 1.3 ton so there's less load on the engine, and you won't have the lean burn fuel settings I've heard the later Range Rover v8's had?

I know with some of the diesels I've messed about with getting the temperature up torwards 100 degrees makes them run a lot better than 70-80 degrees.
 
I think I'm close to having a view that the cooling of the "tower" between the carbs is critical to their proper performance. This based on work you and Duncan have done at Petworth and my own experience with them. Lack of cooling in the tower leads rapidly to all sorts of problems, vaporisation being the least of them. Sooo.. I'm a bit shifty about upping the coolant temperature on two scores. The first is keeping the tower sufficiently cool. The second is that the higher coolant temperature in Rangies and Discos appears to be associated with liners moving. We could have a debate about whether the true cause is the block casting accuracy, the design temperature or the actual temperature experienced with a less than perfect cooling system. But I'd rather not take the risk. I think I'd want to run it at the standard 85.

Chris
 
Hi Jim,

Ideally you should retain your P6B crankshaft pulley with the attached damper. This ensures correct alignment with the PAS pump. If you intend running a different alternator, then the bracket as you mentioned will need fabricating to suit. Whether or not the pulley on the P38 water pump will align with the others will remain to be seen.

Persuing the P38 timing cover and the corresponding 96 degree C thermostat, which will see a normal running temp of 100 degrees C or so, will place additional stress on the P6B cooling system hoses. The radiator cap will need changing to an 18psi replacement at the very least. Thermo fans will need to installed to keep the temp within reasonable limits. You'll also need to use a semi synthetic oil as the running temp takes it above the optimum running temp for mineral oils, which is in the 83 to 92 degree range, as measured within the sump.

Top hat liners will also be highly advisable so as to avoid potential problems down the track. Running with an 82 degree C stat you could probably have side stepped that issue, but the much higher temps places it right back centre stage again.

Keeping the SU carburettors, which were not designed to function at such an elevated temperature, may see fueling problems arise, due to the low fuel pressure that they require.

Ron.
 
Just looking on Ebay, Range Rover P38 thermostats appear to be remote units, not integral to the engine, and fitting the SU manifold would retain the stock P6 thermostat?

Another point is the 4.6 is complete, and very likely to be exactly as it was when it came from the factory, I think P6 crank pulleys were balanced to the engine, not sure about the later ones?

Converting single V to serpentine really isn't a big issue for someone who has basic tools and skills, and everything is already there on the engine.

Regarding the power steering pump, what are the pulley ratios of each engine and what is the supplied pressure of the pump, surely that would give an indication of it's suitability?

How does the P6 pulley attach to the pump, most modern power steering pumps I've come across have a very similar 3 bolt mounting on the pulley?
 
Hi Simon,

The P38 water pump runs in the opposite direction, hence the reason the thermostat was mounting down in the bottom radiator hose. So the coolant flow would be in the opposite direction, flowing into and not out of the inlet manifold. Not sure if using an 82 degree C stat in the opposite orientation would be successful. :?

The P6B power steering pump pulley is retained by one central bolt. I run the P6B crankshaft pulley and damper on my 4.6 crankshaft without issue.

I seem to remember that the P38 timing cover also has a different design in terms of the interface with the RR sump. That may be another issue that would need a resolution in order to run the P6B sump with that timing cover.

Ron.
 
This is getting interesting isn't it? :)
Searching the internet for similar situations I found an Australian forum with people running cooler stats in their 4L and 4.6L engines
http://www.aulro.com/afvb/discovery-2/159639-82-thermostat-4l-v8.html

I'm sure you've read all this before but thought it worth posting in one place on the subject.

According to Des Hammill (How to power tune Rover V8 engines for road and track), LR increased the engine operating temperature to 96*C in GEMS managed engines (1995 onwards) to meet more stringent emission requirements.
John Eales / JE Engineering, never found cracked blocks/slipped liners to be an issue in their race engines which run much lower temperatures (typically 60 to 80*C) while under considerably more stress.

If a cooler stat could be used in the location of the 4.6 one, or if a different remote housing could be employed, would the system not just run cooler?
Other than the direction of flow, what differences would there be essentially?

If I'm using the 4.6 front cover, is there a fitment reason why I can't use the 4.6 sump too?

More from John Eales:
"Maximum power is produced by any Rover v8 when coolant temperature is maintained at an optimum 75 degrees C (167F).
On the other hand, if the temperature is allowed to rise to say, 100 degrees C (212F) the engine power drops off by 10%. Controlling the engine's coolant temperature is clearly critical for power production as well as limiting block expansion. Aim to keep the water temperature at 75 degrees C
All carburettor equipped engines can be set to run at 75 degrees C and the fitting of a 72 degrees C thermostat will do this"

So running it cooler is what I originally wanted with the p6 timing cover arrangement as you have done Ron, but it seems to be possible to do what we're suggesting, just logistics of fitting?

Jim
 
Hi Jim

Sorry mate, I'm unclear what you and Ron are suggesting...

I see no problem with using the carbs and the P38 front cover, just so long as you run it all nice and cool. There shouldn't be any difficulty acquiring a remote stat housing to insert into the bottom hose. The carb tower being fed directly from the rad output could be a marked improvement, but there will be some re-plumbing required there.

Chris
 
Chris, that's exactly what I was suggesting :D
As you know this particular configuration doesn't get put together often, I think Ron was raising questions on the remote thermostat location suitability
Jim
 
Measuring up today I noticed my headers sitting on the bench, calling to me :LOL:
So I popped off a p38 manifold and bolted one on to see how well they fit, which seems to be fairly good straight out the box



Jim
 
I've just read that the ZF power steering pump has upto 1500psi output.
I have no idea what it would be at idle etc, or in use?
How does this compare with the P6b pump?
Thanks
Jim
 
corazon said:
I've just read that the ZF power steering pump has upto 1500psi output.
I have no idea what it would be at idle etc, or in use?
How does this compare with the P6b pump?
Thanks
Jim
Click to expand...




Re: PAS Pump Pressure?

Postby harveyp6 on Mon Sep 30, 2013 4:25 pm
With a pressure guage between the HP hose and the box, the steering held on full lock, and with the engine at 1000rpm the pressure should be 850-950psi, allow to idle, 400psi minimum, and then with the steering backed off from lock, 100psi maximum at idle. Don't hold it on lock for too long....
 
Thanks Harvey, I just found that topic from Tom 302Rover after I posted :D
So it could be too powerful then? I don't know how these pumps operate..I wonder if it could be stepped down in any way?
Would it pump to it's maximum by default do you think?
I'll do more research on the zf pumps.
Jim
 
The ultimate pressure will be controlled by a relief valve, so you could tweak that, and increasing the size of the pump pulley relative to the crank pulley will effectively reduce the pressure at any given point in the range.
 
Incidently if you do end up mixing and matching pumps and crank pulleys I have a crank pulley with at least two auxilliary pulleys that I would split and sell according to your needs.
 
Hi Jim,

The Rover V8 engines are all very similar, but also all very different. Does indeed make life interesting!

The use of the P38 sump isn't an option as its size will impact on the P6B engine cross member. You have to use the P6B sump, which will also need to be modified (relieved) for clearance prior to fitting to the 4.6 block.

If you can source an alternative remove thermostat housing which will allow the fitment of either a 72 or 82 degree C stat, for location within the bottom radiator hose, then that will certainly have wide spread benefits.

I actually disagree with Chris (sorry Chris) on the suggestion that proper cooling of the tower is essential so as to prevent fuel vapourisation issues. The primary reason coolant flows through the inlet manifold is for heating purposes, as it greatly assists in atomisation of the fuel, especially at low temperatures.

Ron.
 
coolant through intake manifold it to prevent carb icing-----ran mine without coolant---not too good so have to agree with SydneyRoverP6B on that point
 
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